DE NORA TETRA® Biological Filtration


The robust nature of DE NORA TETRA® filters creates an ideal environment for simultaneous biological and physical/chemical treatment. De Nora has over 50 years of experience removing nutrients, organic compounds, and solids in teriary fixed-film biological filters. Common applications include polishing municipal wastewater effluent to reuse standards and/or regulatory discharge limits. Potable applications combine De Nora ozone and biological filtration technologies to oxidize micropollutants and to mitigate disinfection byproduct formation.

DE NORA TETRA® biofilters can be designed in a variety of configurations to achieve optimal treatment for biological oxidation of organic compounds, nitrification, and denitrification. The De Nora flagship biofilter with over 300 installations is DE NORA TETRA® Denite® system, which biologically reduces soluble nitrates to nitrogen gas in an anoxic environment. In addition to nitrogen removal, DE NORA TETRA® Denite®solution often employs physical/chemical processes to enhance performance by also removing phosphorus and solids in a single-stage process. Media selection is influenced by a DE NORA TETRA® DeepBedTM filtration concept that is especially advantageous for biological applications where reaction time, solids holding capacity, and biomass inventory control are critical to performance.
DE NORA TETRA® ColOXTM, SAFTM, and NSAFTM are aerobic biofilters used for BOD/COD oxidation and nitrification.


  • History of proven performance
  • Excellent distribution of backwash air and water keeps filter media clean
  • High loading capacity and superior performance at peak loads
  • No small openings, nozzles, screens or moving parts to clog or wear
  • Low dirty backwash water return volume; longer filter run times
  • Easy to upgrade existing De Nora media filters to biologically active mode
  • Can accommodate wide range of media types and sizes